Mr, as you say that your lower part of front portion of teeth has become black. It seems like you have stains deposited on your teeth. You have to get your teeth professionally cleaned by a dentist. But blackening may happen due to some other reasons also:
1. May be due to intrinsic stains (paan or tobacco chewing)
2. Due to cavity.
3. Due to any old trauma to the tooth.
So visit a nearest dentist in your area for further need and expert advise, as a clinical examination will reveal the proper cause.

Hello ,
your front tooth has turned black.this shows you had some trauma in the teeth some years ago.
and now it has become non vital.
you need to have RCT of teeth and then place a crown over it.
This will help you to improve the esthetic of your teeth

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